A Canberra forum on paid maternity leave has been told mothers rank affordability in child care as the most important policy to help them return to work after giving birth.

The forum is looking at the effect of the Federal Government's introduction of paid maternity leave last year.

Melbourne Institute researcher Guyonne Kalb says a survey by the Longitudinal Study of Australian Children found child care cost was ranked higher than accessibility and quality.

She says the results are useful when considering ways to help women return to the workforce.

"With this sort of introduction of paid maternity leave, I think the next thing is to look at, after they've had their maternity leave, how can they return to the labor force in straight forward ways," she said.

Ms Kalb says inflexible workplaces mean some women never return to the workforce after giving birth.

"When you're interested in maintaining a reasonably large labor force and keeping women up to date with their skills, then the provision of part time work is really important," she said.

The forum also heard many mothers are being excluded from the workforce because of a lack of part-time opportunities.